Rolling bearings usually are used to support a load between parts that rotate relative to each other. For example, rolling bearings regularly are positioned between a stationary shaft and a rotating member, such as a gear, pulley, sprocket, brake, or clutch or between a rotating shaft and a stationary member, such as a housing. For numerous applications the rolling bearings are press fit onto the shaft and into the rotating member. Also, for many applications, a certain degree of bearing pre-load is desirable. For example, when a mechanical device employing a rolling bearing is operated under a heavy load, a pre-load often is used in order to minimize the axial and radial end play clearances between the rolling elements and the inner and outer races. The pre-load reduces deflection of the bearing resulting from a load that is applied directly to the shaft or the rotating member. Furthermore, the pre-load improves the running conditions of a bearing that is operated under a dynamic load.
When double tapered roller bearings are press fit onto the shaft and into the rotating member, one cone and the cups typically are seated against shoulders or snap rings on the shaft and in the rotating member. The other cone remains movable so that an operator can make an axial adjustment to the other cone in order to set a pre-load for the bearings.
Presently, multiple ram strokes are used to install sets of double tapered roller bearings onto the posts of a planet pinion carrier of a planetary transmission. The standard procedure for installing planet pinions is basically as follows. A pilot stud is aligned with each post. The pilot studs have diameters slightly less than the diameters of the posts. Next, the following items are mounted on each pilot stud in the order listed: an inner bearing cone and roller set; an annular inner tool for moving the inner bearing cone and roller set; an inner bearing cup; a planet pinion that has a spacer for separating a set of double tapered roller bearings; an outer bearing cup; and an annular outer tool for moving the outer bearing cup. Each inner tool engages both the inner bearing cone and cup and has internal and external diameters that permit free movement on the pilot stud and in the planet pinion, respectively. Each outer tool engages its respective outer bearing cup and has internal and external diameters that permit free movement on the pilot stud and in the planet pinion, respectively.
The carrier then is aligned with rams that are moved through a first stroke into engagement with the outer tools and toward the posts. This movement forces the inner bearing cones and roller sets onto the posts and forces the cups into the planet pinions and against the spacers. Next, the planet pinions, including the pressed-in cups, plus the inner and outer tools are removed from the pilot studs.
The planet pinions with the pressed-in races are returned to the pilot studs and an outer bearing cone and roller set is mounted on each pilot stud. The carrier is realigned with the rams which are moved through a second stroke into engagement with the outer bearing cones, forcing the outer bearing cones and roller sets into the planet pinions and onto the posts. After withdrawal of the rams and removal of the pilot studs, the pre-load for each of the sets of double tapered roller bearings is set using washers and cap screws. The operator tightens the washers and cap screws in order to yield a preselected torque required for rotation of the planet pinions.
Shortcomings of multiple strokes include wasted assembly time, poor equipment utilization, and excess exposure of bearing parts to contaminants and damage.